Chen, Yuxuan (2024) Investigation of faults in air-conditioning systems in commercial buildings: Occurrence, diagnostic validation, and energy impacts. PhD thesis, University of Nebraska - Lincoln, USA.
Abstract
In commercial buildings, fault detection and diagnosis (FDD) tools have been developed for detecting and diagnosing faults in building systems, which can provide useful information regarding fault locations and potential causes of faults, so that building operators and facility staff can be notified in time and quickly respond as problems arise. Nowadays, there are many commercial FDD tools available in the market, and these tools have been widely adopted in large- and medium-scale commercial buildings in the United States. Several studies have demonstrated the energy saving potential with the use of FDD in commercial HVAC systems, and one critical aspect of the considerations of faults is their prevalence which can indicate the commonality of faults over a course of time, and provide insights into fault prioritization. Prevalence of different fault types with respect to different systems and equipment has been reported based on FDD results in multiple studies, but limited efforts have been seen on a broad scale to validate if the FDD results are valid and the prevalence is reflective of the true frequency. This dissertation presents the estimate of fault prevalence and field studies validating the FDD results for six FDD providers, covering a variety of faults in package rooftop units (RTUs), air-handling units (AHUs), and air terminal units (ATUs) in different buildings. Fault metrics regarding prevalence are developed, and fault prevalence in terms of fault types is calculated for all FDD tool providers. Regarding the validity of FDD tools, comparisons between the field results and the FDD results are performed. Although results show that false positives and false negatives exist, we still find that field results and FDD fault conditions are in good agreement. In addition, an essential part of this dissertation is to investigate the energy impact of the faults. By simulating selected faults in medium-scale and large-scale commercial prototype buildings through EnergyPlus software, impacts with respect to energy consumption and indoor thermal comfort are demonstrated and evaluated when HVAC system is operating under different faulty conditions. Advisor: David P. Yuill
| Item Type: | Thesis (Doctoral) |
|---|---|
| Thesis advisor: | Lau, Josephine; Liu, Xiaoqi (Clare) and Cheng, Xiaoyue (Zoe) |
| Uncontrolled Keywords: | air terminal unit; air-handling unit; building energy modeling; commercial HVAC systems; HVAC fault diagnostics; packaged rooftop unit; architectural engineering; architecture; construction engineering and management |
| Index terms: | dissertation, estimate, energy-saving, construction engineering, architectural engineering, energy consumption, building system, investigation, thermal comfort, validity, energyplus, package, commercial building, validation, prototype, field study, energy modelling, United States |
| Subjects: | data collection methods, engineering systems, modelling and simulation, sustainability and energy, financial and cost management, energy systems, engineering methods, design practice, professional development, environmental engineering, research dissemination and communication, evaluation and assessment methods, construction type, contractual arrangements, environmental science, research methods, Geography |
| Topics: | Engineering Principles, Geographical Context, Sustainability, Procurement, Design Practice, Information Management, Research Practice, Cost Management, Construction Technology |
| Descriptive scope: | 3 PCA |
N.B. Descriptive scope is a count of how many of the five facets of empirical research are indicated by the words used in title, abstract and keywords. It is not intended as a judgement on the research; merely a count of the kind of word we would expect to indicate Phenomenon, Concepts, Theoretical framing, Empirical techniques, Analytical techniques. If all five are present, then a code of “5 PCTEA” will indicate this. If you feel the coding for this record is questionable, we welcome discussion around the terms we matched or the way we categorized them. The facet you would expect may not be coded, or a facet may be coded inappropriately. This can also bear on a larger question, of which facets should be treated as defining in construction management research. Please get in touch, and we will look at it. More details here